#include <iostream>
#include <vector>
using namespace std;

int main() {
	int n,m;
	cin>>n>>m;
	vector<vector<double>> dp(n+1,vector<double>(m+1));
	dp[0][0]=1;
	for(int i=1;i<=n;++i){
		dp[i][0]=dp[i-1][0]*0.2;
		for(int j=1;j<=min(i,m);++j){
			dp[i][j]=dp[i-1][j]*0.2+dp[i-1][j-1]*0.8;
		}
	}
	printf("%.4lf",dp[n][m]);
	
	return 0;
}
